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Chapter 3: SICK Optic LMS 200
3.1 Sensor Background
Although it has been assumed from the early stages of the project that measuring
the distance and orientation of an MBC with respect to the mine walls is essential to
computing a path plan, simulation and dynamic analysis performed Aishwarya Varadhan
and Amnart Kanarat have validated this assumption. Their efforts have established a
control strategy requiring a line-finding algorithm capable of locating each MBC in the
CHS with respect to the mine walls. The evolving algorithm requires measurement
devices with the ability to sample mine walls with multiple data points in less than a
second. To accomplish this task, either an array of point measurement or swept
measurement devices can be used. Ultrasonic sensors and stationary laser devices are
typically used for point measurements. Some laser measurement devices that can
perform sweeping measurements by deflecting the laser beam by rotating optics are
available.
In trying to determine the most suitable technologies, several factors must be
examined. Quite prevalent, ultrasonic sensors can require a lot of expertise to ensure
accurate and reliable operation. Acoustical reverberation from surrounding structures
and cross talk between sensors can be serious problems. Ultrasonic sensors are typically
quite cheap to use, so they have a strong economic benefit for the project budget. The
performance and benefit of a swept laser measurement device appears proportional to
their cost; they are typically quite expensive. The more intelligent the line-finding
algorithm needed to become meant the increasing need for a swept laser sensor. Instead
of requiring an array of point devices to measure the position of an MBC in the mine, a
single swept laser would be capable of measuring all objects within a 180° range of the
scanner. A decision on the technology to use was not made for some time, so efforts
focused on both developing ultrasonic sensors, developing a swept scanner and procuring
a commercial swept laser measurement device.
Even though testing had been done with the ultrasonic sensors, results from
continued simulation studies showed that a swept measurement device was ideal for the
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